Method for filling a hydrogen storage container

ABSTRACT

Described is a method for filling a storage container with a gaseous, pressurized medium, preferably with gaseous, pressurized hydrogen. 
     According to the invention, a determination of the internal storage container pressure takes place at the onset of the filling process by means of a pressure test impact and a filling process with time-controlled pressure increase up to the desired internal storage container pressure takes place subsequently as a function of the established internal storage container pressure.

The invention relates to a method for filling a storage container with a gaseous, pressurized medium, preferably with gaseous, pressurized hydrogen.

Generic methods for filling a storage container are used, for example, when filling vehicle storage containers or tanks, respectively, with pressurized hydrogen. Vehicle tanks can be filled up to pressures of 700 bar at 15° by means of such filling processes.

It is required hereby that the filling process can be realized for the most diverse vehicle tank sizes without an overfilling and/or overheating of the vehicle tank. Currently, the hydrogen filling station communicates with the vehicle, which is to be fueled, either via a communication cable, which, as a rule, is integrated in the filling coupling or via an infrared interface.

Due to the information received from the vehicle tank, which is to be filled, such as pressure, temperature, etc., a special controlled-flow control valve is actuated by means of a PLC evaluation so as to be able to independently fuel different vehicle tank sizes. The afore-mentioned controlled-flow control valve has the object of holding the flow-through within a predetermined range and to prevent the exceeding of a flow-through upper limit. The control does not only serve for or determine, respectively, the correction of the current mass flow rate, but furthermore initiates a fueling interruption in the event that the flow-through is too low or too high.

With presently realized filling stations for gaseous, pressurized hydrogen, the hydrogen flow-through is limited to maximally 100 g/s by means of a firmly adjusted choke. However, with comparatively small vehicle tank sizes—this refers to storage volumes comprising a capacity of less than 75 liters—the result can be an overheating of the vehicle tank, which is to be filled, due to the negative Joule-Thompson effect and due to the adiabatic compression of the hydrogen. The filling of such vehicle tanks is thus not possible with common filling stations for gaseous, pressurized hydrogen.

However, due to the fact that the automobile industry demands the independence of the vehicle tank design and thus also of the vehicle tank size, the person of skill in the art is assigned the object of specifying a generic method for filling a storage container with a gaseous, pressurized medium, preferably with hydrogen, which avoids the afore-mentioned disadvantages and which provides for a filling of the most diverse vehicle tank sizes, without leading to an overfilling and/or overheating of the vehicle tank.

To solve this object, a generic method for filling a storage container with a gaseous, pressurized medium, preferably with hydrogen, is proposed, said method being characterized in that a determination of the internal storage container pressure takes place at the onset of the filling process by means of a pressure test impact and that a filling process with time-controlled pressure increase up to the desired internal storage container pressure takes place subsequently as a function of the established internal storage container pressure.

According to the invention, a determination of the internal storage container pressure now takes place at or prior to the onset, respectively, of the actual filling process. A so-called pressure test impact, which on the one hand checks the impermeability of the established mechanical connection between coupling and vehicle, and which on the other hand, provides for a clear determination of the internal storage container pressure, is realized for this purpose after the fixing of the fueling coupling to the vehicle, which is to be fueled.

As a function of the internal storage container pressure, which is established in such a manner, a filling process with time-controlled pressure increase up to the desired internal storage container pressure is then realized. For this purpose, the final pressure is computed as a function of the parameters storage container, temperature, gas temperature, compressibility and Joule-Thompson effect, after establishing the starting pressure. The fueling or filling process, respectively, is finished when this computed final pressure or the maximum operating pressure, which is permissible for the maximum operating temperature, of the storage container, which is to be fueled, has been reached.

The method according to the invention for filling a storage container with a gaseous, pressurized medium, preferably with hydrogen, effectively avoids an overfilling and/or overheating of the storage container, which is to be filled, independent on the storage volume thereof.

The method according to the invention for filling a storage container furthermore encompasses the advantage that, due to the realized, controlled pressure increase, the storage container, which is to be filled, can accommodate more mass of medium, which is to be stored, because the temperature increase can be controlled and is the same for each storage container size due to the method according to the invention. The complicated control engineering, which has been required until now, as well as the afore-mentioned components, such as infrared interface, etc., are no longer necessary.

The fact that the filling or fueling process, respectively, is less extensive, because the connection of a communication cable, which “connects” the vehicle, which is to be fueled, to the filling station, which was required up to now, represents further advantages of the method according to the invention for filling a storage container with a gaseous, pressurized medium; this is advantageous in particular when the filling procedure is performed by unqualified personnel. The disadvantages connected with the infrared interfaces, which were used up to now, such as interruption due to an incident, for example, can be avoided from now on.

It is emphasized that the method according to the invention for filling a storage container with a gaseous, pressurized medium is not limited to the filling of a storage container with gaseous, pressurized hydrogen. Instead, the method according to the invention can be used in all media, for which a controlled pressure increase is desired or required during the filling process. 

1. A method for filling a storage container with a gaseous, pressurized medium, preferably with gaseous, pressurized hydrogen, characterized in that a determination of the internal storage container pressure takes place at the onset of the filling process by means of a pressure test impact and that a filling process with time-controlled pressure increase up to the desired internal storage container pressure takes place subsequently as a function of the established internal storage container pressure. 